Group 3 Facsimile: The mode of black and white facsimile
operation , defined in
ITU-T Recommendation T.4, that incorporates means for reducing the redundant
information in the
signal by using a one-dimensional
run -length
coding scheme prior to the
modulation process.
Note 1: A 216 ª 279-mm document,
i.e. , an 8½ ª 11-inch document, may be transmitted in approximately 1 minute or less over a
telephone -type
circuit with twice the Group 2
horizontal resolution . The vertical resolution may also be doubled.
Note 2: Group 3 Facsimile machines have integral
digital modems.
Note 3: An optional two-dimensional
bandwidth compression scheme is also defined within the Group 3 Facsimile Recommendation.
Note 4: When any
CCITT or
CCIR Recommendation is modified by the ITU-T, the modified document is designated as an
ITU-T Recommendation.
Group 3C Facsimile: The Group 3
digital mode of facsimile
operation defined in
CCITT Recommendation T.30.
Note: Group 3C is also referred to as Group 3 Option C or as Group 3-64 kb/s.
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